1. Technical Field
The present invention relates to a method and apparatus for detecting an envelope for ultrasonic signals.
2. Description of the Related Art
An ultrasonic B-mode image may be made by using high-frequency pulses with a wide frequency bandwidth. The emitted ultrasonic pulses may be reflected off an object in their original form and be inputted to a transducer.
The reflected signals may be composed of pulses continuing along the time axis, and a 2-dimensional imaging of these signals results in an image in which there are high-frequency components remaining. By detecting the envelope, it is possible to remove the high-frequency components and leave only the target of which imaging is desired.
In thus removing high-frequency components to image the target, the detection of the envelope is an essential procedure.
A technique for detecting the envelope by using the Hilbert Transform (Malene Schlaikjer, Jan P. Bagge, Ole M. Sorensen, and Jorgen Arendt Jensen, “Trade off study on different envelope detectors for B-mode imaging” Ultrasonics, 2003 IEEE Symposium) can provide ideal results, but the implementation method is complicated and may incur high costs and long computation times.
A technique employing in-phase quadrature demodulation (Jin Ho Chang, Jesse T. Yen, and K. Kirk Shung, “A Novel Envelope Detector for High-Frame Rate, High Frequency Ultrasound Imaging” IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 54, no. 9, Sep. 2007) may involve choosing a center frequency, applying sine and cosine functions, and passing the results through a low-pass filter.
However, if the center frequency is not chosen correctly, the modulation may not be done accurately, and the detection of the envelope may not be properly achieved.
As such, there is a demand for a technique that enables not only accurate envelope detection but also a decrease in the time required for envelope detection.
In particular, since ultrasound diagnosis additionally requires the processing of various signals and images, there is a growing need for a technique that allows faster processing of ultrasonic data.